1. Field of the Invention
The present invention relates to an image display device, a head-mounted display, and a light beam expanding device.
2. Description of the Related Art
A virtual-image display device (image display device) for allowing the viewer to view a two-dimensional image formed by an image forming device as an enlarged virtual image by a virtual-image optical system is known from e.g. JP-T-2005-521099 and Japanese Patent Laid-open No. 2006-162767.
As shown in a conceptual diagram of FIG. 14, this image display device 200 includes an image forming device 201 including plural pixels arranged in a two-dimensional matrix, a collimating optical system 202 for turning light output from the pixels of the image forming device 201 to collimated light, and an optical guide unit 203 on which the light turned to the collimated light by the collimating optical system 202 is incident. The incident light is guided in the optical guide unit 203 and output therefrom. The optical guide unit 203 is composed of an optical guide plate 204, a first deflector 205 (formed of e.g. one light reflective film), and a second deflector 206 (formed of e.g. a light reflective multilayer film having a multilayer-stacked structure). The light incident on the optical guide plate 204 is propagated inside the optical guide plate 204 by total reflection and then output therefrom. The first deflector 205 reflects the light incident on the optical guide plate 204 so that this light may be totally reflected inside the optical guide plate 204. The second deflector 206 makes the light propagated inside the optical guide plate 204 by total reflection be output from the optical guide plate 204. If e.g. a head-mounted display (HMD) is formed by using such an image display device 200, reduction in the weight and size of the device can be achieved.